Hepatocyte Growth Factor (HGF) is a potent mitogen and motogen for many epithelial cells and has been suggested to promote invasiveness in breast cancer. We have documented potent effects of HGF on human bronchial epithelial cells and non-small cell lung cancer cells (NSCLC). HGF stimulates DNA synthesis, cell growth and cell movement in these cells in a paracrine fashion. HGF produced by cultured fibroblasts derived from the lung mediates these responses, and we have also documented using the in situ reverse transcriptase-polymerase chain reaction that mesenchymal cells in the lung that are in close association with the surface and glandular epithelium produce HGF. We also have preliminary evidence that HGF is a strong negative prognostic indicator for lung adenocarcinoma, and that HGF administered to human airway xenografts can increase tumor invasion and growth in vivo. The goal of this revised application is to continue these studies by further investigating the ability of HGF to stimulate growth and invasion in NSCLC, the effect of inhibiting its action using two different approaches, and the mechanism by which it acts to increase invasiveness. Five Specific Aims are described: (1) To study the ability of HGF to stimulate in vivo growth and invasion in human airway xenografts, and to utilize an HGF antagonist to inhibit effects of HGF; (2) To use the U6 expression plasmid to deliver antisense sequences for HGF and c-met to lung fibroblasts and lung carcinoma cells, respectively, and determine the effect on in vitro and in vivo growth and invasion; (3) To study the mechanism of HGF stimulaiton of lung tumor invasion by measuring activation of the MAP kinsae-ets pathway by HGF and increased transcription of genes for proteases, important in breakdown of the extracellular matrix, that are regulated by the ets family of transcription factors; (4) To create a transgenic A/J mouse strain that expresses HGF in the airway epithelial cells under the control of the CC10 Clara cell promoter and perform tumorigenesis studies with urethane and methylnitrosourea to determine if overexpression of HGF in the epithelial microenvironment leads to an increased incidence of lung cancer and (5) To determine if HGF is a negative prognostic indicator for squamous cell and large cell NSCLC, as well as adenocarcinoma.